Environmental control systems and methods of configuring environmental control systems

ABSTRACT

An environmental control system of a building utilizes lower vents which open into lower portions of rooms of a building, and upper vents which open into upper portions of rooms of the building. When the system is operating in a heating mode, heated air is delivered into the upper portions of the rooms through the upper vents and air is removed from the rooms through the lower vents. When the system is operating in a cooling mode, cool air is delivered into the rooms through the lower vents, and air is removed from the rooms through the upper vents. Operating the heating and cooling modes in this fashion provides the most efficient operation of the heating and cooling system. A switching unit is used to selectively couple the inlet and outlet of an air handling unit to the upper and lower vents.

FIELD OF THE TECHNOLOGY

The disclosed technology is related to heating and cooling systems used to heat and cool rooms of a building.

BACKGROUND

Heating and cooling systems for buildings typically include a heating unit which produces heated air and a cooling unit which produces cool air. The hot or cool air is then delivered into rooms of a building through ducts and vents which open into the rooms. In addition, it is common to include air return vents and ducts which return air from one or more rooms of a building back to the heating unit or cooling unit. Thus, air is circulated from the heating and cooling unit, into the rooms, and then back to the heating and cooling unit.

The placement of the vents which deliver heated or cooled air into a room, and the placement of return vents which pull air back out of a room can vary depending on the building design. It is common to place such vents in the walls of a room, in the floor of a room, or in the ceiling of a room.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a heating and cooling system which is operating in a heating mode;

FIG. 2 is a diagram illustrating a heating and cooling system operating in a cooling mode;

FIGS. 3A and 3B are perspective views of a switching unit for a heating and cooling system configured in first and second operational modes, respectively;

FIGS. 4A and 4B are perspective views of another embodiment of a switching unit for a heating and cooling system configured in first and second operational modes, respectively;

FIG. 5 is a diagram of the placement of vents in the rooms of a building;

FIG. 6 is a diagram illustrating an alternate placement of vents within the rooms of a building;

FIG. 7 is a perspective view of a switching unit which includes multiple potential I/O ports configured in a first operational mode;

FIG. 8 is a perspective view of the switching unit in FIG. 7 configured in a second operational mode;

FIG. 9 is a perspective view of a switching unit which includes multiple input and output ports;

FIG. 10 is a front view of a switching unit which includes a motorized switching device;

FIG. 11 is a perspective view of a pyramid-shaped switching unit;

FIGS. 12A and 12B are top views of the pyramid-shaped switching unit of FIG. 11 with the switching plate in two different positions;

FIG. 13 is a diagram of a cylindrical-shaped switching unit coupled to a heating and cooling unit;

FIG. 14A is a perspective view of the core of the cylindrical-shaped switching unit of FIG. 13;

FIG. 14B is a front view of the cylindrical-shaped core of the switching unit of FIG. 14A;

FIG. 14C is a left side view of the cylindrical-shaped core of the switching unit of FIG. 14A;

FIGS. 15A and 15B illustrate an alternate embodiment of a switching unit;

FIGS. 16A and 16B illustrate yet another alternate embodiment of a switching unit;

FIGS. 17A and 17B illustrates a heating and cooling unit that is capable of reversing the flow direction of air passing through the unit;

FIG. 18 illustrates another embodiment of a heating and cooling unit that is capable of reversing the flow direction of air passing through the unit;

FIG. 19 illustrates an another alternate embodiment of a heating and cooling unit that is capable of reversing the flow direction of air passing through the unit;

FIGS. 20A and 20B illustrate another alternate embodiment of a switching unit;

FIG. 21 illustrates the elements of an environmental control system for a large building that incorporates a switching unit.

FIGS. 22A and 22B illustrate how an environmental control system incorporating a switching unit can be operated to help clear a building of smoke in the event of a fire;

FIGS. 23A and 23B illustrate a duct that can selectively deliver or remove air to/from either a lower or an upper duct opening;

FIG. 24A illustrates a room with multiple ducts as illustrated in FIGS. 23A and 23B operating in a cooling mode;

FIG. 24B illustrates a room with multiple ducts as illustrated in FIGS. 23A and 23B operating in a heating mode;

FIG. 25 illustrates a room similar to the one illustrated in FIGS. 24A and 24B where one switchable duct unit is replaced with a simple vent opening;

FIGS. 26A and 26B illustrate a room with fixed lower supply vents and return ducts that can pull air from upper or lower parts of the room operating in heating and cooling modes;

FIGS. 27A and 27B illustrate a room with fixed upper supply vents and return ducts that can pull air from upper or lower parts of the room operating in heating and cooling modes;

FIGS. 28A and 28B illustrate a room with fixed lower return vents and supply ducts that can supply air to upper or lower parts of the room operating in heating and cooling modes;

FIGS. 29A and 29B illustrate a room with fixed upper return vents and supply ducts that can deliver air to upper or lower parts of the room operating in heating and cooling modes;

FIGS. 30A and 30B illustrate an alternate form of a wall duct that can be used as either a return duct or a supply duct;

FIG. 31 is a perspective view of another embodiment of a switching unit coupled to a supply duct, a return duct, and ducts running to high and low vents into a room;

FIGS. 32A-32C are top, front and right side views, respectively, of a switching unit as illustrated in FIG. 31 in a first rotational position;

FIGS. 33A-33C are top, front and right side views, respectively, of the switching unit as illustrated in FIG. 31 in a second rotational position;

FIG. 34 is a perspective view of another embodiment of a switching unit having movable shutters;

FIG. 35 illustrates a switching unit as shown in FIG. 34 installed in a duct system;

FIG. 36 illustrates another embodiment of a simple switching unit that can be installed in a duct system as illustrated in FIG. 35;

FIG. 37 illustrates another embodiment of a simple switching unit that can be installed in a duct system as illustrated in FIG. 35;

FIG. 38 illustrates another embodiment of a simple switching unit that can be installed in a duct system as illustrated in FIG. 35;

FIG. 39 illustrates another embodiment of a switching unit installed in a duct system;

FIGS. 40A and 40B illustrate a switching unit as shown in FIG. 39 with shutters in a first switching position;

FIGS. 41A and 41B illustrate a switching unit as shown in FIG. 39 with shutters in a second switching position;

FIG. 42 is a perspective view of another embodiment of a switching unit that could be installed in a duct system as illustrated in FIG. 39; and

FIG. 43 is a top view of the switching unit shown in FIG. 42.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In a heating and cooling system embodying the invention, at least two vents are provided within a room of a building. An upper vent is positioned at an upper portion of the room, and a lower vent is positioned in a lower portion of the room. As shown in FIG. 1, the heating and cooling system would include a heating and cooling unit 100 which is connected to a switching unit 200.

The heating and cooling unit could take numerous different forms. It could be a traditional gas or electric furnace, paired with a traditional air conditioning unit. In other instances, it could be a heat pump. In other instances, it could take other forms. Regardless of the actual form of the device, it would be capable of delivering both heated air for heating rooms of a building, and cooled air for cooling rooms of a building. While certain sections of the following description refer to a heating and cooling unit, this term is meant to refer to any device or devices capable of delivering heated and/or cooled air.

The switching unit 200 would be connected to a first duct 302 which is connected to the upper vents that open into upper portions of the rooms of a building. The switching unit would also be connected to a lower duct 304 which is connected to lower vents 305 a, 305 b, 305 c, 305 d which open into lower portions of the rooms of a building 300.

FIGS. 3A and 3B illustrate one embodiment of a switching unit 200 which can be used in the heating and cooling system illustrated in FIGS. 1 and 2. As shown in FIG. 3A, the switching unit 200 includes an input port 204 which is attached to the upper right side of a front wall 250 of the switching unit 200. In addition, an output port 202 is provided in a lower left side of the front wall 250.

A first input/output (I/O) port 212 is provided on a rear face of the switching unit. In addition, a second I/O port 214 is also provided on the rear face of the switching unit. Note, the first I/O port 212 is located on the upper right side of the rear face of the switching unit, and the second I/O port 214 is provided on the lower left side of the rear face of the switching unit.

A rectangular switching plate 230 is rotatably mounted inside the switching unit 200. In the embodiment shown in FIG. 3A, the switching plate 230 is mounted on two pivot points 232, 234 located on the front and rear faces of the switching unit. This allows the switching plate to rotate between a horizontal position, as shown in FIG. 3A, and a vertical position, as shown in FIG. 3B.

When the switching plate 230 is located in the horizontal position, as shown in FIG. 3A, air entering the switching unit 200 through the input port 204 can be communicated to the first I/O port 212. Air entering the switching unit through the second I/O port 214 can be communicated to the output port 202.

When the switching plate 230 is rotated to the vertical position, as shown in FIG. 3B, the connections are changed. As shown in FIG. 3A, when the switching plate is oriented vertically, the air entering the input port 204 will be communicated to the second I/O port 214. Likewise, air entering the switching unit through the first I/O port 212 will be communicated to the output port 202.

The ability to change how the input port 204 and output port 202 of the switching unit are coupled to the two I/O ports 212, 214 makes it possible to change how heated and cooled air is delivered to and removed from the rooms of a building. This capability also makes it possible to increase the efficiency of a typical heating and cooling system of a building.

FIGS. 4A and 4B show another embodiment of a switching unit 200 in first and second operational conditions. As is apparent, the width of the second embodiment is approximately half the width of the embodiment illustrated in FIGS. 3A and 3B. The width of this type of a switching unit can be changed to suit the area in which the switching unit is to be mounted. It may be necessary, in some situations, to reduce the width of the switching unit to accommodate the available mounting space.

FIG. 1 illustrates the heating and cooling system when it is operating in a heating mode. In other words, FIG. 1 shows the system when heated air is being delivered into the rooms of the building 300. As shown in FIG. 1, heated air from the heating and cooling unit 100 is delivered to an input port of the switching unit 200. The heated air is then communicated to an upper duct 302 which is connected to upper vents 303 a, 303 b, 303 c, 303 d located in the upper portions of the rooms of the building 300.

If the switching unit shown in FIGS. 3 and 4 were used in the heating and cooling systems shown in FIGS. 1 and 2, the output of the heating and cooling unit 100 would be connected to the input port 204 of the switching unit 200. Likewise, the output port 202 of the switching unit would be coupled to the input of the heating and cooling unit 100. The upper duct 302 would be coupled to the first I/O port 212, and the lower duct 304 would be coupled to the second I/O port 214.

When the system is operating in the heating mode, as illustrated in FIG. 1, the switching plate would be oriented horizontally, as shown in FIG. 3. As a result, the heated air delivered from the heating and air conditioning unit 100 to the input port 204 of the switching unit 200 would be communicated to the upper duct 302, which is coupled to the first I/O port 212. The heated air would be delivered to the upper portions of the rooms of the building via the upper vents 303 a, 303 b, 303 c and 303 d.

In addition, air would also be simultaneously removed through the lower vents 305 a, 305 b, 305 c, 305 d of the rooms of the building. The air removed from the rooms would be communicated through the lower duct 304 which is attached to the second I/O port 214 of the switching unit 200 shown in FIG. 3. The air removed from the rooms of the building would then exit the switching unit 200 through the output port 202, and the air would be communicated through an output duct 104 back to the heating and cooling unit 100. The air returned to the heating and air conditioning unit 100 through the output duct 104 would then be heated and sent back to the switching unit 200 through duct 102.

FIG. 2 illustrates the same system operating in a cooling mode. In the cooling mode, the heating and cooling unit 100 would be supplying cooled air to the switching unit 200 through the duct 102. The switching unit would be configured as shown in FIG. 4, where the switching plate 230 is oriented vertically. As a result, the cooled air delivered into the input port 204 of the switching unit 200 would be delivered to the second I/O port 214. The second I/O port 214, which is connected to the lower duct 304, would ensure that the cooled air is then delivered to the lower portions of the rooms of the building 300 through the lower vents 305 a, 305 b, 305 c, 305 d.

At the same time, air would be removed from the rooms of the building through the upper vents 303 a, 303 b, 303 c, 303 d. The air removed from the upper portions of the rooms would travel along the upper duct 302 to the first I/O port 212 of the switching unit 200. Because the switching plate 230 is oriented vertically, as shown in FIG. 4, the air removed from the rooms of the building entering the switching unit 200 through the first I/.O port 212 would then be communicated to the output port 202 of the switching unit 200. The air removed from the rooms of the building would then be sent through the duct 104 back to the heating and cooling unit 100. The air received back from the rooms of the building would then be cooled and sent back to the switching unit 200 through the duct 102.

When a heating and cooling system is configured as illustrated in FIGS. 1 and 2, it is possible to operate the system in two different modes. In the heating mode, as shown in FIG. 1, the heated air is delivered to the upper portions of the rooms through the upper vents, and air is removed from the rooms through the lower vents. Conversely, when the system is operating in a cooling mode, as shown in FIG. 2, cooled air is delivered to the lower portions of the rooms through the lower vents, and air is removed from the rooms through the upper vents.

The coolest air within the rooms would be located in the lower portions of the rooms. As a result, when the heating and cooling system is operating in the heating mode, the coolest air within the rooms will be sucked into the lower vents and returned back to the heating and air conditioning unit so that it can be reheated. The flow pattern within the room would be from the top to the bottom of the room. And because the warmer air would normally be located at the upper portions of the room, this air flow pattern will help to better distribute the heated air down to the lower portions of the room.

Conversely, when the system is operating in the cooling mode, as shown in FIG. 2, the cooled air is first delivered to the lower portions of the room, and air is removed from the upper portions of the room. Again, the warmest air within the room will be located in the upper portions of the room. By removing the warmer air from the upper portions of the room, the warmest air in the room will be removed first. In addition, the flow pattern for the air within the room will be from the bottom to the top. This helps to distribute the relatively cooler air from the bottom of the room into the upper portions of the room.

It is believed by the inventor that operating the heating and cooling system in these two different heating and cooling modes will result in the most efficient heating and cooling of the rooms of the building. Operating in this fashion will also ensure that in the heating mode, heated air is redistributed to the coolest portions of the room in a more effective fashion, and in the cooling mode, cooled air will be redistributed to the warmest portions of the room in the most efficient fashion.

The actual locations of the upper and lower vents can vary from one installation to another. As shown in FIG. 5, in some instances the lower vents 322 a, 322 b, 322 c, 322 d can be located within the floor of the rooms of the building 300. The lower ducts may be coupled to a lower duct 320 running underneath the floor of the building. Likewise, the upper vents 312 a, 312 b, 312 c, 312 d could be located within the ceiling of the building. The upper vents could be attached to an upper duct 310 which runs through the ceiling or possibly in the attic of the building.

In alternate instances, as shown in FIG. 6, the upper vents 312 a, 312 b could be located in walls of the rooms. Likewise, the lower vents 322 a, 322 b could also be located within the walls of the rooms. In still other instances, the upper vents could be located in a ceiling, while the lower vents are located in either the walls or the floor of a room. Likewise, the lower vents could be located in the floor, whereas the upper vents are located in the walls of the rooms.

The actual locations of the upper and lower vents is somewhat unimportant so long as the lower vents are located in a lower portion of a room, and the upper vents are located in an upper portion of a room.

In the switching unit illustrated in FIGS. 3 and 4, the input port 204 and output port 202 are formed on a front wall of the switching unit, whereas the first I/O port 212 and the second I/O port 214 are located on an opposite rear wall of the switching unit. In alternate embodiments, it would be possible to move the first and second I/O ports and/or the input port and output port to different locations.

FIGS. 7 and 8 illustrate a switching unit which is similar to the one shown in FIGS. 3 and 4. In FIGS. 7 and 8, the input port 204 and the output port 202 are still located on a front wall 250 of the switching unit. However, FIGS. 7 and 8 illustrate a plurality of alternate locations for the first I/O port and the second I/O port. As shown therein, the first I/O port 212 could also be located at the positions identified with reference numerals 213 a, 213 b, 213 c, and 213 d. Likewise, the second I/O port 214 could be located at the alternate locations identified with reference numerals 216 a, 216 b, 216 c, and 216 d.

FIG. 7 depicts the switching unit 200 where the switching plate 230 is oriented horizontally. As a result, the input port 204 will deliver air to the first I/O port 212. However, if the first I/O port 212 were moved to one of the alternate locations 213 a, 213 b, 213 c and 213 d, air entering through the input port 204 would be delivered to the first I/O port at any of these alternate locations.

Air entering the switching unit through the second I/O port 214 would be communicated to the output port 202. And if the second I/O port 214 were moved to one of the alternate locates 216 a, 216 b, 216 c, 216 d, the air entering the switching unit through any of these alternate locations would still be communicated to the output port 202.

FIG. 8 shows the switching unit after the switching plate 230 has been oriented to a vertical position. As a result, air entering the switching unit 200 through the input port 204 would be communicated to the second I/O port 214, or to any of the alternate locations 216 a, 216 b, 216 c, 216 d. Likewise, air entering the switching unit through the first I/O port 212 would be communicated to the output port 202 regardless of whether it enters through the rear face of the switching unit or through one of the alternate locations 213 a, 213 b, 213 c, 213 d.

FIGS. 7 and 8 illustrate that the first and second I/O ports can be moved to different locations on the switching unit 200 while still preserving the same basic functionality of the sidewalls switching unit. The first and second I/O ports could also be moved to selected locations on the top and bottom surfaces. However, the input port 204 and the output port 202 can also be moved to different locations on the switching unit without altering the basic functionality of the switching unit.

Depending on where the switching unit is installed in a building, and depending upon the ducting arrangement required for the installation, it may be advantageous to attach the first and second I/O ports to one of the alternate locations on the switching unit. Likewise, it may be advantageous to move the input port and the output port to an alternate location. Moving the first and second I/O ports and/or the input port and output port to an alternate location might result in a small decrease in the efficiency of the switching unit, due to air flow losses. However, locating one of the I/O ports or the input port or output port at an alternate location may be necessary to accommodate the particular arrangement within the building.

In addition, in the embodiments shown in FIGS. 3, 4, 7 and 8, only a single duct is shown attached to the first I/O port, and only a single duct is attached to the second I/O port. In alternate embodiments, as shown in FIG. 9, a plurality of ducts may act as I/O ports. In the embodiment shown in FIG. 9, the first I/O port has been replaced with two first I/O ports 212 a, 212 b located on a side face of the switching unit (the alternate locations). Likewise, the second I/O port 214 has been replaced with two second I/O ports 214 a, 214 b located on another side face of the switching unit (the alternate locations).

Similarly, the embodiments shown in FIGS. 1-4, 7 and 8, show only a single duct attached to the input port 204, and only a single duct attached to the output port 202. In alternate embodiments, multiple ducts could deliver heated and cooled air from the heating and cooling unit 100 to the switching unit 200, and the multiple ducts could be attached to switching unit at multiple locations. Likewise, multiple ducts could deliver air returning from the rooms from the switching unit 200 to the heating and cooling unit, and the multiple ducts could be attached to switching unit at multiple locations. Further, in some embodiments, multiple ducts might deliver heated and cooled air from the heating and cooling unit to the switching unit, while only a single duct delivers return air from the switching unit to the heating and cooling unit, and vice versa.

As noted above, the rectangular or square switching plate 230 within the switching unit is rotatably mounted on two pivot points 232, 234. In some embodiments, the user might manually rotate the switching plate 203 between the horizontal and vertical orientations using a lever or knob attached to the switching plate in order to switch the system from the heating to the cooling mode, or vice versa. Some type of locking system could also be provided to lock the switching plate in either the horizontal or vertical position.

In other embodiments, a power device could be used to move the switching plate 230 between the horizontal and vertical orientations. FIG. 10 illustrates an embodiment in which an electric motor 240 is coupled to a drive belt 244 via a pulley 242. The drive belt 244 is also attached around a pulley 246 which is attached to a rotational axis of the switching plate 230. As a result, rotation of the motor 240 will cause the switching plate 230 to rotate between the horizontal and vertical orientations.

Note, in some embodiments, the switching plate 230 could be moved 90 degrees clockwise, and then 90 degrees counterclockwise to switch the switching plate 230 back and forth between the horizontal and vertical orientations. In other embodiments, the switching plate could simply be rotated clockwise 90 degrees at a time to move the switching plate between the vertical and horizontal orientations.

In alternate embodiments, a different type of powered switching means could be used to cause the switching plate to move between the vertical and horizontal orientations. The motor illustrated in FIG. 10 is only one non-limiting embodiment. For instance, the switching unit could be a rack and pinion arrangement, a hydraulically or pneumatically operated piston arrangement, a linear motor arrangement, or any other type of device which can be used to impart rotational motion, as is well known to those skilled in the art.

Moreover, the switching units illustrated in FIGS. 3, 4 and 7-10 are all rectilinear units having square or rectangular switching plates. In alternate embodiments, the switching unit could take on a variety of other forms. Regardless of the specific form of the switching unit, however, the switching unit should preferably be capable of switching the heated and cooled air output by a heating and cooling unit between the upper vents in a room and the lower vents in a room.

FIG. 11 is a perspective view of a pyramid-shaped switching unit which could also be used in a system embodying the invention. As illustrated in FIG. 11, a triangular-shaped switching plate 420 is rotationally mounted within the triangular-switching unit 400. FIGS. 12 a and 12 b illustrate a top view of the triangular-shaped switching unit 400 shown in FIG. 11. In FIG. 12 a, the switching plate 420 is oriented in a first position. In FIG. 12 b, the switching plate 420 has been rotated 90 degrees so that it is oriented in the second position.

The triangular-shaped switching unit includes an input port 402, and an output port 404. In addition, the triangular-shaped switching unit includes a first I/O port 412 and a second I/O port 414.

When the triangular-shaped switching plate 420 is oriented as shown in FIG. 12 a, heated or cooled air entering in an interior of the switching unit through the input port 402 would be communicated to the first I/O port 412. Likewise, air returning from rooms of a building entering the switching unit through the second I/O port 414 would be communicated to the output port 404.

When the switching plate 420 is rotated to the position shown in FIG. 12 b, the input port 402 would be connected to the second I/O port 414. Also, the first I/O port 412 would be connected to the output port 404.

As also illustrated in FIGS. 11, 12 a and 12 b, the input port, output port and first and second I/O ports could be located at alternate locations. For instance, the input port 402 could also be located at the position marked with reference numeral 403. The output port 404 could also be located at the alternate position identified with reference numeral 405. The first I/O port 412 could be located at the alternate position 413. Further, the second I/O port 414 could be located at the alternate position 415.

Furthermore, as explained above, two input ports could be provided at locations 402 and 403, and two output ports could be located at positions 404 and 405. Likewise, two first I/O ports could be located at positions 412 and 413, and two second I/O ports could be located at positions 414 and 415.

FIG. 13 illustrates the use of a cylindrical-shaped switching unit in a heating and cooling system embodying the invention. The cylindrical switching unit 500 has a cylindrical shaped core 502, as illustrated in FIG. 14A, mounted inside a cylindrical outer shell. The cylindrical core 502 is rotated 90 degrees inside the outer shell to change how the output vent 102 and input vent 104 are coupled to an upper duct 302 and a lower duct 304.

FIG. 14 a shows a perspective view of the core 502 of the cylindrical switching unit 500 illustrated in FIG. 13. As shown in FIG. 14 a, the cylindrical core 502 includes an upper horizontal duct 510 passing between two upper horizontal ports 511, 512. The core also includes a lower horizontal duct 520 passing between two lower horizontal ports 521, 522. When the core 502 is rotated so that the upper horizontal port 511 is connected to the output duct 102, the opposite upper horizontal port 512 would be connected to the upper duct 302. Further, the lower horizontal port 521 would be connected to the duct 104, and the opposite lower horizontal port 522 would be connected to the lower duct 304.

When the core 502 of the switching unit is rotated 90 degrees, the upper and lower horizontal ducts 510, 520 would no longer be in registration with the upper duct 302, lower duct 304, or the ducts 102 and 104 passing to the heating and cooling unit 100. Instead, a first vertical duct 530 would connect the output duct 102 to the lower duct 304 passing to the building. Also, the second vertical duct 540 would connect the upper duct 302 from the building to the input duct 104 passing into the heating and cooling unit.

FIG. 14B presents a front view of the core 502 of the cylindrical-shaped switching unit, and FIG. 14C presents a left side view of the core 502 of the cylindrical switching unit 500. FIGS. 14B and 14C are provided to better illustrate the connections provided by the horizontal ducts 510 and 520, and the vertical ducts 530 and 540.

In the description provided above, it was assumed that the heating and cooling unit 100 would provide both heated air during a heating operation and cooled air during a cooling operation. In alternate embodiments, the heating and cooling unit 100 might only include a heater, or it might only include an air conditioning unit. For instance, if a building is located in a warm climate area, there would be no need for the building to include a heater. Instead, the building would only have an air conditioning unit. Likewise, if a building is located in a cool climate area, the building might only include a heater, and it would not have an air conditioning unit. Benefits of the above-described systems could also be obtained by buildings having only a heater or only an air conditioner.

If a building includes only a heater, the switching unit would be set into the heating mode when the heater is being operated to provide heated air into the rooms of the building. If, on a particular day, the outside temperature becomes unusually warm, it would be possible to set the switching unit into the cooling mode, and then run the system with just a fan to circulate air. Although the air provided into the rooms of the building would not be cooled by the heating and cooling unit 100, the air would still circulate. And the movement of cooler air at the bottom of each room towards the top of each room, resulting from the airflow caused when the switching unit is in the cooling mode, would still serve to better distribute the cool air in the rooms. Thus, some benefit would be provided by operating the system in the cooling mode, with just a fan running, even though no air conditioning unit is cooling the air passing through the heating and cooling unit 100.

Likewise, if a building only includes an air conditioning unit, the switching unit would be set into the cooling mode when the air conditioning unit is running. If a particular day is unusually cool, the switching unit could be switched to the heating mode, and the air could simply be circulated with a fan. Although no heater would heat the air passing through the heating and cooling unit 100, simply moving the air in the heating mode would serve to better distribute the warmer air at the tops of the rooms down towards the bottoms of each room. Thus, some benefit would be obtained from running the system in the heating mode with just a fan.

In view of the foregoing, the inventor believes that a system as described above can be beneficial even for buildings that have only a heater or only an air conditioning unit.

FIGS. 15A and 15B illustrate an alternate embodiment of the switching unit. In these drawing figures, the switching unit is illustrated with dashed line 200.

The switching unit includes two crossing ducts 602 and 604, both of which pass between the output duct 102 and the input duct 104 of the heating and cooling unit 100. Two movable damper flaps 612 and 618 are located at opposite ends of the first crossing duct 602. Likewise, two damper flaps 614 and 616 are located at opposite ends of the second crossing duct 604.

When the switching unit 200 is operating in the heating mode, as illustrated in FIG. 15A, the damper flaps 612, 614, 616 and 618 are in the positions illustrated in FIG. 15A. As a result, heated air from the heating and cooling unit 100 passes from the output duct 102 straight through to the duct 302 which is connected to vents in the upper portions of the rooms of a building. Likewise, the duct 304, which is connected to vents in lower portions of the rooms of a building, is directly connected to the input duct 104 to heating and cooling unit 100.

The switching unit 200 can be switched into a cooling mode, as illustrated in FIG. 15B, by moving the damper flaps to the positions illustrated in FIG. 15B. As a result, cool air leaving the heating and cooling unit 100 through the output duct 102 is routed to the duct 304 connected to vents in the lower portions of the rooms of a building. Likewise, the air being removed from the upper portions of the rooms through the duct 302 is coupled to the input duct 104 passing into the heating and cooling unit 100.

FIGS. 16A and 16B illustrate another alternate embodiment that is similar to the one shown FIGS. 15A and 15B. In this embodiment, only two of the damper flaps are provided. Specifically, the damper flap 614 and the damper flap 618 are included, but the remaining damper flaps are removed. FIG. 16A illustrates the alternate embodiment operating in a heating mode, and FIG. 16B illustrates the alternate embodiment operating in a cooling mode.

FIGS. 17A and 17B illustrate yet another alternate embodiment of a heating and cooling system which does not require the use of a switching unit. In this embodiment, the heating and cooling unit 700 includes a cooling core 708, a heating core 706 and a fan 710 that can be rotated to blow air in different directions.

When the fan 710 is oriented as illustrated in FIG. 17A, the fan will draw air from a duct 304 connected to the lower vents in the rooms of a building, and the fan 710 will blow air into a duct 302 connected to the upper vents in the rooms of the building. Thus, the system would be operated as illustrated in FIG. 17A during a heating mode.

However, it is possible to rotate the fan 90 degrees clockwise into the position illustrated in FIG. 17B, which effectively reverses the flow direction of the air. Thus, the system would be operated as illustrated in FIG. 17B during a cooling mode.

The rotatable fan 710 could be manually rotated between the two positions by a user when the user wishes to switch between the heating and cooling modes. In other embodiments, a power mechanism may be provided to automatically orient the fan in the appropriate position depending on whether the system is operating in the heating or cooling mode.

In other alternate embodiments, the rotatable fan could be positioned above the heating core 706 and cooling core 708. In still other embodiments, the fan could be located at an interim position between the bottom and the top of the heating and cooling unit 700. In this instance, the fan might rotate 180 degrees to reverse the flow direction of the air.

FIG. 18 illustrates another embodiment of a heating and cooling unit that does not require a switching unit to reverse the air flow directions. In this embodiment, the heating and cooling unit 700 includes a first fan 702 and a second fan 704. Also included is a cooling core 708 and a heating core 706.

When the embodiment illustrated in FIG. 18 is to be operated in the heating mode, the first fan 702 will be activated to blow air into the duct 302 passing to the upper portions of each of the rooms of a building. The heating core 706 would be activated to heat the air which is being delivered into the upper portions of the room. Air returning from the rooms through the duct 304 connected to the lower portions of the rooms would then be received back into the lower portion of the heating and cooling unit 700.

When the system is operated in a cooling mode, the lower fan 704 would be activated. In addition, the cooling core 708 would cool air passing through the heating and cooling unit 700. As a result, cool air would be delivered to the lower portions of the rooms through the duct 304 connected to the lower portions of the rooms. Air removed from the upper portions of the rooms through the duct 302 would be delivered back into the upper portion of the heating and cooling unit 700. By providing two different fans 702 and 704, it is possible to reverse the flow direction of the air without the use of the separate switching unit.

FIG. 19 illustrates yet another alternate embodiment which includes a bi-directional fan 710. This embodiment would operate in a fashion similar to the embodiments described above. However, in this embodiment, the bi-directional fan 710 would be capable of reversing the air flow direction without the use of an additional separate fan unit, and without the need to rotate the fan 710.

FIGS. 20A and 20B illustrate another alternate embodiment of a switching unit. In this embodiment, a helical-shaped switching plate 910 is rotationally mounted inside a cylindrical housing 900. The helical switching plate twists around 90° from the top of the cylindrical housing 900 to the bottom of the cylindrical housing 900. The helical switching plate 910 is itself capable of being rotated at least 90° between first and second positions.

The cylindrical housing 900 has an upper circular end cap and a lower circular end cap. Two apertures 902, 904 are formed on opposite sides of the upper end cap. Likewise, two apertures 912, 914 are formed on opposite sides of the lower end cap. Similar to the embodiments discussed above, ducts running to upper and lower vents in the rooms of a building would be attached to the apertures 912, 914 on the lower end cap, while ducts running to the inlet and outlet of the heating/cooling unit would be attached to the apertures 902, 904 of the upper end cap, or vice versa.

FIG. 20A shows the helical switching plate 910 in a first position. In this position, the helical switching plate couples the first aperture 902 on the upper end cap to the second aperture 914 on the lower end cap. Also, the second aperture 904 on the upper end cap is coupled to the first aperture 912 on the lower end cap. With the helical switching plate 910 in this position, the apertures in the upper and lower end caps could be connected to one another so as to deliver air from a heating/cooling unit to upper portions of the rooms of a building. Air would also be removed from the lower portions of the rooms of a building and delivered back to the heating/cooling unit.

FIG. 20B shows the helical switching plate in a second position. In this position, the helical switching plate couples the first aperture 902 on the upper end cap to the first aperture 912 on the lower end cap. Also, the second aperture 904 on the upper end cap is coupled to the second aperture 914 on the lower end cap. With the helical switching plate 910 in this position, the apertures in the upper and lower end caps could be connected to one another so as to deliver air from a heating/cooling unit to lower portions of the rooms of a building. Air would also be removed from the upper portions of the rooms of a building and delivered back to the heating/cooling unit.

Although the switching unit illustrated in FIGS. 20A and 20B has apertures in certain locations on the upper and lower end caps, in alternate embodiments, these locations could be varied while achieving the same or different aperture-to-aperture coupling effects. Also, the apertures could instead be placed on the upper and lower portions of the sidewall of the cylindrical aperture. In still other embodiments, some of the apertures could be located on the upper and/or lower end caps, while other apertures could be located on the cylindrical sidewall. Various considerations such as the mounting location of the switching unit could dictate where the apertures are best placed.

Moreover, in this embodiment, the helical switching plate has a 90° twist from the top to the bottom of the cylindrical housing. In alternate embodiments, the helical switching plate could have more or less of a twist from the top to the bottom of the housing.

Further, although not shown in the drawings, a motor or other power operated device could be provided to cause the helical switching plate to move between the first and second positions. In other embodiments, a handle coupled to the helical switching plate might protrude through either the cylindrical sidewall or the upper or lower end cap to allow a user to manually move the helical switching plate between the first and second positions.

Also, because the housing is cylindrical, the helical switching plate could rotate 90° backwards and 90° forwards to switch between the first and second positions. Or, in alternate embodiments, the helical switching plate could rotate 90° forwards to switch from the first position to the second position, and then 270° forward to switch from the second position back to the first position. Thus, the helical switching plate could be configured to always rotate in the same direction.

Switching units as described above can also be used in environmental control systems that are used in large buildings, such as warehouses, large warehouse-style retail stores, or simply in large retail establishments. The basic arrangement of the elements of one such environmental control system is illustrated in FIG. 21.

As shown in FIG. 21, a heating and air conditioning unit 1010 would be mounted on the top of a building. Both a “conditioned” air duct 1012 and a return air duct 1014 would extend down through the roof from the outdoor unit 1010 into the building. The two ducts would be coupled to a switching unit 1020. The switching unit could be any of the above-described embodiments, or alternate embodiments.

The switching unit 1020 is also coupled to an lower air duct 1040 and an upper air duct 1030. The lower air duct 1040 leads to a plurality of lower vent units 1042 which are located in the lower portion of the building. The upper air duct 1030 leads to at least one upper vent unit 1032 located in an upper portion of the building. In the embodiment illustrated in FIG. 21, there are three lower vent units 1042 coupled to the lower air duct 1040, and one upper vent unit 1032 coupled to the upper air duct 1030. However, in alternate embodiments, different numbers of the upper and lower vent units could be used, depending on the configuration of the building, and the heating and cooling needs.

The switching unit 1020 allows the interconnections between the conditioned air duct 1012 and the return air duct 1014 on the one hand, and the lower air duct 1040 and the upper air duct 1030 on the other hand, to be switched. Thus, when the exchanger unit is in heating configuration, the conditioned air duct 1012 would be coupled to the upper air duct 1030, and the return air duct 1014 would be coupled to the lower air duct 1040. When the exchanger unit is in a cooling configuration, the conditioned air duct 1012 would be coupled to the lower air duct 1040, and the return air duct 1014 would be coupled to the upper air duct 1030.

In a traditional large building, the ducts leading to the outdoor unit are connected to the vents units inside the building the same way all year round. However, when heating a building, greater overall efficiency can be obtained when the ducts and vents are coupled to each other in a first way as opposed to a second way. And when cooling the building, greater overall efficiency can be obtained when the ducts and vents are reverse connected. Thus, the provision of the switching unit 1020 allows the interconnections between the ducts and vents to be switched to the maximum efficiency configuration at all times. This results in a greater year-round efficiency for the building.

FIG. 21 illustrates a single outdoor heating and cooling unit 1010 that would be mounted on the roof of a building, and a single upper air duct and lower air duct. However, in a large building, multiple such outdoor units and associated ducting would likely be provided. Also, in individual embodiments, different arrangements of the upper and lower air ducts and vent units could be provided. For instance, multiple upper vent units may be provided instead of just one.

FIGS. 22A and 22B illustrate how an environmental control system incorporating a switching unit can be used to help clear smoke from rooms of a building in the event of a fire. FIG. 22A illustrates a typical building 300 having rooms with upper vents 303 a, 303 b, 303 c, 303 d and lower vents 305 a, 305 b, 305 c and 305 d. A switching unit 200 is connected to an upper duct 302 which is connected to the upper vents that open into upper portions of the rooms. The switching unit 200 is also connected to a lower duct 304 which is connected to the lower vents which open into lower portions of the rooms.

An input duct 104 connects the heating and cooling unit 100 and the switching unit 200. The input duct carries air returning from building 300 back into the heating and cooling unit 100.

An output duct 102 also connects the heating and cooling unit 100 to the switching unit 200. The output duct carries heated and/or cooled air from the heating and cooling unit 100 to the switching unit. However, a bypass duct 106 is also connected to the output duct 102. The bypass duct 106 simply vents to the atmosphere outside the building 300. A bypass valve 108 is located at the junction between the bypass duct 106 and the output duct 102.

When the bypass valve is in the closed position, as illustrated in FIG. 22A, the bypass duct 106 is isolated from the output duct 102, and the heated or cooled air output from the heating and cooling unit 100 is conveyed to the switching unit. However, when the bypass valve 108 is in the open position, as illustrated in FIG. 22B, the air output from the heating and cooling unit is routed into the bypass duct 106, and out to the surrounding atmosphere. The bypass valve prevents the air output from the heating and cooling unit 100 from reaching the switching unit.

FIG. 22A illustrates the system operating normally in a cooling mode. As illustrated in FIG. 22A, cooled air is output from the heating and cooling unit 100 to the switching unit 200. The switching unit couples the cooled air to the lower duct 304, and the cooled air is delivered into the rooms of the building through the lower vents 305 a, 305 b, 305 c and 305 d.

FIG. 22B illustrates a situation where a fire has been detected in the building. As shown in FIG. 22B, a fire 307 in one of the rooms has produced smoke 308, which tends to collect at the upper portion of the room. When the fire is detected, such as by a fire alarm system, the bypass valve 108 is switched from the closed position to the open position. As a result, cooled air produced by the heating and cooling unit 100 is no longer provided to the switching unit 200, or into the lower portions of the rooms through the lower vents 305 a, 305 b, 305 c and 305 d. However, the heating and cooling unit 100 will continue to operate. As a result, the heating and cooling unit 100 will continue to pull air from the rooms through the upper vents 303 a, 303 b, 303 c and 303 d. And this will help to clear the smoke from the upper portions of the rooms. The smoke and air pulled from the rooms will go through the upper duct 302 into the switching unit 200, then on to the heating and cooling unit 100 via the input duct 104. The smoke and air will then pass through the heating and cooling unit 100 and along the output duct 102 and the bypass duct 106 out into the atmosphere. Thus, the continued operation of the heating and cooling system 100 with the bypass valve in the open position will help to clear smoke from upper portions of the rooms of the building 300.

If the system was operating in the heating mode when a fire is detected, this would mean that heated air is being delivered into the top portion of the room, and that air is being removed from the vents at the lower portion of the room. When the fire is detected, the switching unit 200 would be switched to the cooling mode so that air is being removed from the top portions of the room, which would help to clear the smoke that collects at the top of the room. Also, the bypass valve 108 would be switched to the open position, as illustrated in FIG. 22B, so that the air pulled from the top portions of the rooms and which passes through the switching unit 200 and the heating and cooling unit 100 is vented to the atmosphere through the bypass duct 106.

FIGS. 23A and 23B illustrate a specialized duct that can be installed in rooms of a building to achieve the same basic heating and cooling effects that are obtained with the switching units described, but without the need for a separate switching unit. As illustrated in FIGS. 23A and 23B, the duct 1100 includes an inlet/outlet 1106, a lower duct opening 1104 and an upper duct opening 1102. A valve 1110 is installed in the duct adjacent the lower duct opening 1104. The valve can move between a first position as illustrated in FIG. 23A, in which it closes off the upper duct opening 1102, and a second position as illustrated in FIG. 23B, in which it closes off the lower duct opening 1104.

The valve 1110 could be controlled by an electronically operated drive mechanism such that electrical signals can be used to cause the valve to move between the first and second positions. In alternate embodiments, the valve 1110 might be manually operated. If the valve is manually operated, the operating mechanism that is used to move the valve between the first and second positions could be accessible to a user through the lower duct opening 1104 to allow the user to easily change the valve position.

FIG. 24A shows how two or more of the ducts 1100 could be installed in walls 309 of a room 301. The lower duct openings 1104 would open into lower vents 305 a, 305 b into the room 310. The upper duct openings 1102 would open into upper vents 303 a, 303 b into the room. The inlet/outlet 1106 of the ducts would be located beneath the floor of the room.

As illustrated in FIG. 24A, the inlet/outlet 1106 of the duct shown on the left side of the room 301 is coupled to the outlet duct 102 of an air handling unit 100. The inlet/outlet 1106 of the duct 1100 on the right side of the room is coupled to the inlet duct 104 of the air handling unit 100. As with the other embodiments described above, the air handling unit would be capable of outputting either heated or cooled air from the outlet duct 102. And the air handling unit 100 would receive air from the rooms of the building via the inlet duct 104.

In the configuration shown in FIG. 24A, the air handling unit would be in cooling mode. This means that the air handling unit would receive air from the rooms of the building via the air inlet duct 104, and the air handling unit would cool the air, and then output the cooled air via the outlet duct 102. As shown in FIG. 24A, the valve 1110 of the duct 1100 connected to the outlet duct 102 is in a position that shuts off the upper duct opening 1102. Thus, the cooled air from the air handling unit 100 is delivered into the room through the lower duct opening 1104. Because the valve 1110 of the other duct 1100 which is connected to the inlet duct 104 is shutting off the lower duct opening 1104, the air being returned from the room to the air handling unit is pulled into the upper duct opening 1102 at the top of the room. Thus, the system is operating in a cooling mode as described above, where cool air is delivered into the lower portion of a room, and air is removed from the upper portion of the room.

In the configuration illustrated in FIG. 24B, the positions of the valve 1110 within the ducts 1100 have been reversed. Thus, air from the air handling unit 100 is delivered into the upper portion of the room through the upper duct opening 1102 of the duct 1100 connected to the outlet duct 102. Also, air being returned to the air handling unit 100 via the inlet duct 104 is pulled from the lower portion of the room via the lower duct opening 1104 of the duct 1110 on the right side of the room. This configuration would be appropriate when the air handling unit is delivering heated air in a heating operational mode.

In still other embodiments, one of the two duct units illustrated in FIGS. 24A and 24B could be replaced with a simple vent opening in the wall of the room. So long at least one of the inlet duct 104 and the outlet duct 102 of the air handling unit 100 are connected to a duct as illustrated in FIGS. 23A and 23B, with switchable upper and lower duct openings, some heating and cooling efficiencies would still be achieved.

FIG. 25 illustrates a room 301 similar to the one illustrated in FIGS. 24A and 24B. However, the switchable duct unit connected to the inlet duct 104 is replaced with a simple vent 306 opening into the room. This embodiment is shown operating in the heating mode. If one of the inlet duct 104 and the outlet duct 102 of the air handling unit 100 is coupled to a simple vent opening in the room, the best heating and cooling efficiency may be achieved where the simple vent opening 306 is located at a position midway between the floor and the ceiling of the room.

FIG. 26A illustrates another example of how a duct as illustrated in FIGS. 23A and 23 b can be utilized in conjunction with fixed vents. In this embodiment, one or more fixed lower vents 311 are connected to the output of the air handling unit 100. In addition, return ducts 1100 capable of pulling air from lower or upper portions of the room are provided in walls of the room. The return ducts 1100 are coupled to the inlet side of the air handling unit 100.

FIG. 26A illustrates the system operating in a heating mode. In this mode, the valves 1110 of the return ducts 1100 are positioned to close off the upper duct openings 1102. As a result, air in the room is pulled into the lower duct openings 1104 and returned to the air handling unit. Heated air is delivered into the room through the fixed lower supply vents 311.

FIG. 26B illustrates the same system operating in a cooling mode. In this mode, the valves 1110 of the return ducts 1100 are positioned to close off the lower duct openings 1104. As a result, air in the room is pulled into the upper duct openings 1102 and returned to the air handling unit 100. Cooled air is delivered into the room through the fixed lower supply vents 311.

FIG. 27A illustrates a room that still includes the return ducts 1100 mounted in the walls, but where the supply vents 313 are mounted in an upper portion of the room. FIG. 27A shows the system operating in a heating mode. Thus, heated air produced by the air handling unit is delivered into upper portions of the room through the fixed upper supply vents 313. The valves 1110 of the return ducts 1100 are positioned to close off the upper duct openings 1102. Thus, air is pulled into the return ducts 1100 through the lower duct openings 1104 and returned to the air handling unit 100.

FIG. 27B shows the same system operating in a cooling mode. In this mode, cooled air from the air handling unit is delivered into the upper portions of the room. The valves 1110 are positioned to close off the lower duct openings 1104. Thus, air is pulled into the return ducts 1100 through the upper duct openings 1102 and returned to the air handling unit 100.

In the embodiments illustrated in FIGS. 26A-27B, the fixed vents were used as supply vents and the ducts with upper and lower duct openings were used as return ducts. However, the functions of the fixed vents and the ducts could be reversed so that the fixed vents are used as return vents, and the ducts act as supply ducts. FIGS. 28A-29B illustrate such embodiments.

FIG. 28A illustrates an embodiment in which one or more fixed lower return vents 311 are connected to the input of the air handling unit 100. In addition, supply ducts 1100 capable of delivering air to lower or upper portions of the room are provided in walls of the room. The supply ducts 1100 are coupled to the outlet side of the air handling unit 100.

FIG. 28A illustrates the system operating in a heating mode. In this mode, the valves 1110 of the supply ducts 1100 are positioned to close off the lower duct openings 1104. As a result, heated air is delivered into the room through the upper duct openings 1102. Air is removed from the room and returned to the air handling unit through the fixed lower return vents 311.

FIG. 28B illustrates the same system operating in a cooling mode. In this mode, the valves 1110 of the supply ducts 1100 are positioned to close off the upper duct openings 1102. As a result, cooled air is delivered into the room through the lower duct openings 1104. Air is removed from the room and returned to the air handling unit 100 through the fixed lower return vents 311.

FIG. 29A illustrates a room that still includes the supply ducts 1100 mounted in the walls, but where the return vents 313 are mounted in an upper portion of the room. FIG. 29A shows the system operating in a heating mode. The valves 1110 of the supply ducts 1100 are positioned to close off the lower duct openings 1104. Thus, heated air produced by the air handling unit 100 is delivered into upper portions of the room through the upper duct openings 1102. Air is removed from the room through the fixed upper return vents 313.

FIG. 29B shows the same system operating in a cooling mode. In this mode, the valves 1110 are positioned to close off the upper duct openings 1102. Thus, cooled air from the air handling unit 100 is delivered into the lower portions of the room. Air is pulled from the room and returned to the air handling unit via the fixed upper return vents 313.

While systems as illustrated in FIGS. 26A-29B are not capable of operating at high efficiency in both heating and cooling modes, they still deliver high efficiency in at least one of those modes. These systems do, however, have relatively simple ducting requirements and they do not require a switching unit as described above.

The systems illustrated in FIGS. 26A, 26B, 29A and 29B will achieve high efficiency in the cooling mode. The systems illustrated in FIGS. 27A, 27B, 28A and 28B will achieve high efficiency in the heating mode. Thus, how the rooms are configured could depend on the location the building. Configurations as illustrated in FIGS. 26A, 26B, 29A and 29B might be preferred in hotter climates where the system will spend more time in the cooling mode. Configurations as illustrated in FIGS. 27A, 27B, 28A and 28B might be preferred in cooler climates where the system will spend more time in the heating mode.

FIGS. 30A and 30B illustrate another alternative design for the wall ducts that include switchable upper and lower duct openings. In this embodiment, a movable switching plate 1120 is slidably mounted inside the duct. The switching plate can be moved from a position as illustrated in FIG. 30A to a position as illustrated in FIG. 30B. When in the position illustrated in FIG. 30A, the switching place closes off the lower duct opening 1104, ensuring that the flow path into or out of the duct is through the upper duct opening 1102. Conversely, when in the position illustrated in FIG. 30B, the switching plate 1120 closes off the upper duct opening 1102, ensuring that the flow path into or out of the duct is through the lower duct opening 1104.

In some embodiments, the switching plate may be configured to come to rest at a position between the positions illustrated in FIGS. 30A and 30B. This would allow a flow path for air entering and leaving the duct to include both the upper duct opening 1102 and the lower duct opening 1104. If the switching plate is held in a middle or intermediate position, that would balance the flow through the upper and lower duct openings. Alternatively, the switching plate could be positioned more to one side or the other of the intermediate position, to cause more of the flow to pass through the upper or lower duct openings.

The switching plate could be moved by a motorized drive unit, or by a manual mechanism. If a manual mechanism is provided to move the switching plate 1120, a lever or knob used to move the switching plate 1120 could be provided at locations easily accessible to the user, such as adjacent the upper and lower duct openings.

FIGS. 31-33C depict another alternate embodiment of a switching unit that can be used to vary how supply and return ducts are coupled to ducts that are routed to high and low vents in a room of a building. As illustrated in FIG. 31, a first side of the switching unit 1200 is mounted closely adjacent to ends of a supply duct 102 and a return duct 104 that are coupled to a heating and/or cooling unit. The supply duct supplies heated and/or cooled air to the switching unit 1200, and the return duct carries air withdrawn from a room back to the heating and/or cooling unit. A second side of the switching unit 1200 is mounted closely adjacent to a first vent duct 302 that is routed to vents positioned in an upper portion of a room, and a second vent duct 304 that is routed to vents position in a lower portion of the room.

The switching unit is rotationally mounted so that it can rotate clockwise and counterclockwise through approximately 90°. As shown in FIGS. 32A-33C, a rotational axis 1230 is provided so that the switching unit 1200 can be rotated between a first position, as illustrated in FIGS. 32A-32C, and a second position, as illustrated in FIGS. 33A-33C.

FIGS. 32A-33C illustrate that there are two internal ducts located inside the switching unit 1200. A first internal duct 1206 couples a first opening 1202 on a first side switching unit 1200 to a second opening 1204 on a second opposite side of the switching unit 1200. A second internal duct 1216 couples a third opening 1214 on the first side of the switching unit 1200 with a fourth opening on the second side of the switching unit 1200. The first and second internal ducts 1206, 1216 traverse diagonal paths through the interior of the switching unit 1200.

When the switching unit is in the first rotational position, as illustrated in FIGS. 31 and 32A-32C, the first internal duct 1206 operatively couples the return duct 104 to the first vent duct 302 that leads to vents in an upper portion of a room. The second internal duct 1216 operatively couples the supply duct to the second vent duct leading to vents positions at a lower portion of the room. As a result, the system will be configured to conduct an efficient cooling operation, where cool air is delivered through the supply duct 102, the switching unit 1200 and the second vent duct to lower vents, while air is withdrawn from the room through upper vents in the room, the first vent duct 302, the switching unit 1200 and the return duct 104.

If the switching unit is rotated 90° counterclockwise from the first position illustrated in FIG. 32B to the second position illustrated in FIG. 33B, the connections between the supply duct 102, the return duct 104 and the first and second vent lines 302, 304 will be reversed. Once the switching unit is rotated to the second position illustrated in FIGS. 33A-33C, the first internal duct 1206 will couple the return duct 104 to the second vent duct 304 leading to the lower vents. The second internal duct 1216 inside the switching unit 1200 will couple the supply duct 102 to the first vent duct 302 leading to the upper vents. As a result, the system will be configured to an efficient heating operation, where heated air is supplied to the upper portion of a room while air is withdrawn from a lower portion of the room.

In some embodiments, the switching unit 1200 would be manually movable between the first position illustrated in FIGS. 32A-C and the second position illustrated in FIGS. 33A-33C. In alternate embodiments, a powered drive unit is used to move the switching unit back and forth between the two positions.

In some embodiments, the switching unit would be rotatable clockwise and counterclockwise to move the switching unit back and forth between the first and second positions. In other embodiments, the switching unit may only rotate in a single direction. In embodiments where the switching unit only rotates in a single direction, the switching unit would rotate 90° to move between the first and the second positions during a first switching operation, and then 270° to return back to the first position during a second switching operation.

In some embodiments, a flexible coupling would be provided between the first and second faces of the switching unit and the open ends of the supply and return ducts 102, 104 and the first and second vent ducts 302, 304 to prevent the escape of air. However, the flexible coupling would allow the switching unit 1200 to rotate between the first and second position.

In alternate embodiments, when it is necessary to rotate the switching unit 1200, the ends of the ducts would be manually or automatically de-coupled from the switching unit 1200, the switching unit 1200 would rotate, and then the ends of the ducts would be re-coupled to the switching unit 1200.

In the embodiment illustrated in FIGS. 31-33C, the switching unit has a rectilinear shape, and the first and second internal ducts 1206, 1216 also have a rectilinear cross-sectional shape. In alternate embodiments, the switching unit could have a circular shape, and the internal ducts could have other cross-sectional shapes.

FIG. 34 illustrates another embodiment of a switching unit that could be used to vary how supply and return ducts are coupled to ducts that are routed to high and low vents in a room of a building. This type of switching unit is designed to interact with a supply duct, a return duct and first and second vent ducts that are arranged in a specific fashion, as illustrated in FIG. 35.

The switching unit 1250 comprises a substantially flat, rectilinear main body 1252. Four apertures 1254, 1256, 1258, 1260 are located in four separate quadrants of the main body 1252. In addition, two shutters 1262, 1264 are rotationally mounted on the main body 1252.

The first shutter 1262 can rotate between a first position as illustrated in FIG. 34, where the first shutter 1262 covers the second aperture to a second position at which the shutter 1262 covers the first aperture 1254 in the main body. In the embodiment illustrated in FIG. 34, the first shutter 1262 is mounted on a rotational shaft 1271 attached to a first motor 1270. Thus, the first motor 1270 can be used to rotate the first shutter 1262 between the first and second positions.

The second shutter 1264 can also rotate between a first position where it covers the fourth aperture 1260 in the main body 1252, to a second position at which it covers the third aperture 1258 in the main body 1252. The second shutter 1264 is mounted on a rotational shaft 1273 coupled to a second motor 1272. Thus, the second motor can be used to rotate the second shutter 1264 between the first and second positions.

As illustrated in FIG. 35, a switching unit as illustrated in FIG. 34 is designed to be mounted in a duct system such that a supply duct 102 and a return duct 104 are adjacent a first side of the switching unit, and vent ducts 302, 304 leading to upper and lower vents in a room, respectively, are adjacent a second opposite side of the switching unit 1250. The side of the switching unit bearing the shutters 1262, 1264 faces the supply duct 102 and the return duct 104.

The supply duct 102 and the return duct 104 have a rectangular shape that extends farther in the horizontal direction than the vertical direction. As a result, the supply duct 102 can operatively communicate with both the first aperture 1254 and the second aperture 1262 on the upper half of the main body 1252 of the switching unit 1250. The return duct 104 can operatively communicate with the third aperture 1258 and the fourth aperture 1260 on the lower half of the main body 1252 of the switching unit 1250.

The vent duct 302 leading to the high vents in the room can operatively communicate with the second aperture 1262 and the third aperture 1258 located on the left side of the main body 1252 illustrated in FIG. 34. The vent duct 304 leading to the lower vents in a room can operatively communicate with the first aperture 1254 and the fourth aperture 1260 located on the right side of the main body 1252 illustrated in FIG. 34.

Because the end of the supply duct 102 is open and has a height greater than a height of the first shutter 1262, the first shutter can rotate between the first position where it covers the second aperture 1256 and the second position at which it covers the first aperture 1254 by swinging through the interior of the supply duct 102. Likewise, because the end of the return duct 104 is open and has a height greater than a height of the second shutter 1264, the second shutter can rotate between the first position where it covers the third aperture 1258 and the second position at which it covers the fourth aperture 1260 by swinging through the interior of the return duct 104.

When the first shutter 1262 and the second shutter 1264 are in the first positions, as illustrated in FIG. 34, the supply duct will only be able to supply air through the first aperture 1254 into the vent duct 304 leading to the lower vents in a room. Also, the return duct will only be able to withdraw air through the third aperture 1258, which is operatively coupled to the vent duct coupled to high vents in the room. As a result, the system will be configured for an efficient cooling operation, where cool air is supplied to the lower portion of a room while air is simultaneously withdrawn from an upper portion of the room.

Rotating the first shutter 1262 to the second position where it covers the first aperture 1254 in the main body 1252 will result open the second aperture 1256 and close the first aperture 1254. As a result, the supply duct will supply air to the vent duct coupled to high vents in the room. Likewise, rotating the second shutter 1264 to the second position where it covers the third aperture 1258 in the main body 1252 will open the fourth aperture 1260 and close the third aperture 1258. As a result, the return duct will withdraw air through the fourth aperture 1260, which is operatively coupled to the vent duct 304 leading to the lower vents in the room. The system will be configured to conduct an efficient cooling operation in which heated air is supplied to the upper portion of a room while air is simultaneously withdrawn from the lower portion of the room.

A switching unit 1250 as illustrated in FIGS. 34 and 35 can switch how the vent ducts are coupled to the supply duct and return duct by switching the positions of the shutters 1262, 1264 under the action of the motors 1270, 1272. Of course, in alternate embodiments, the shutters could be manually moved between the first and second positions to alter how the system is configured.

In other embodiments of the invention, the main body 1252 could be rotated 90° and installed between the ducts such that the shutters 1262, 1264 face the vent ducts 302, 304. In that instance, the shutters would move through the interior of the vent ducts 302, 304 to rotate between the first and second positions to alter the configuration of the system.

FIG. 36 illustrates a switching unit 1290 that can be mounted in a duct system as illustrated in FIG. 35 in two alternate orientations to change the configuration of the duct system. The switching unit 1290 includes a main body 1292 with a first aperture 1294 and a second aperture 1296. The main body also includes a first face 1298 and a second opposite face 1299.

If a switching unit 1290 is shown in FIG. 36 is mounted in the duct system illustrated in FIG. 35 so that the first face 1298 faces the supply duct 102 and the return duct 104, the first aperture 1294 would allow the supply duct to operatively communicate with the vent duct 304 leading to the lower vents. The second aperture 1296 in the main body 1292 would allow the return duct 104 to operatively communicate with the vent duct 302 leading to the high vents. Thus, the system would be configured to conduct an efficient cooling operation.

The system could be reconfigured by removing the switching unit 1290, rotating it 180°, and then re-inserting it between ducts such that the first face 1298 faces the vent ducts 302, 304. When the switching unit is inserted in this orientation, the first aperture would allow the supply duct 102 to operatively communicate with the vent duct 302 leading to the upper vents, and the second aperture would allow the return duct 104 to operatively communicate with the vent duct 304 leading to the lower vents. Thus, the system would be configured to conduct an efficient heating operation.

The switching unit 1290 would most likely be manually moved from the first orientation to the second orientation to switch the system from a heating operation to a cooling operation, and vice versa. However, this switching unit would be inexpensive to produce, and would be less prone to mechanical failures. In addition, it might be easier to provide an effective seal between the ducts the switching unit because there would be no elements needed to switch the shutters that are present in the embodiment illustrated in FIG. 34.

Although the embodiment illustrated in FIG. 36 has the advantage of simplicity, it requires a manual operation to switch between a position that is used to perform cooling operations and a position that is used to perform heating operations. An alternate embodiment which may be easier to automate is illustrated in FIG. 37. In this embodiment, the switching unit 1290 includes a first aperture 1296, a second aperture 1294 and a third aperture 1295. The switching unit 1290 can be slid in the direction of arrows 1293 to selectively align two of the three apertures with the supply and return ducts and with the ducts leading to the high and low vents.

For example, if the switching unit 1290 is positioned between the ducts illustrated in FIG. 35 such that the first aperture 1296 is aligned with the duct 304 leading to the low vents and the second aperture 1294 is aligned with the duct 302 leading to the high vents, then the duct 304 leading to the low vents will be operatively coupled to the return duct 104 and the duct 302 leading to the high vents will be operatively coupled to the supply duct 102. This would configure the system for an efficient heating operation. However, if the switching unit is slid into a new position where the second aperture 1294 is aligned with the duct 304 leading to the low vents and the third aperture 1295 is aligned with the duct 302 leading to the high vents, then the duct 304 leading to the low vents will be coupled to the supply duct 102 and the duct 302 leading to the high vents will be operatively coupled to the return duct 104. Thus, the system will be configured to conduct an efficient cooling operation.

The switching unit 1290 illustrated in FIG. 37 can be slid backwards and forwards to switch the system between heating and cooling operations. And a relatively simple and inexpensive actuator could be used to slide the switching unit 1290 back and forth. Any drive mechanism capable of imparting linear movement in two opposite directions would be suitable.

FIG. 38 illustrates yet another alternate embodiment of a switching unit 1500 suitable for use in a duct system as illustrated in FIG. 35. In this embodiment, the switching unit 1500 includes a first aperture 1502 and a second aperture 1504 which are oriented with respect to each other in an arrangement similar to the one illustrated in FIG. 36. However, this switching unit 1500 is rotationally mounted on an axis 1510. As a result, it is possible to rotate the switching unit 1500 around the axis 1510 in the direction of arrows 1520.

In this embodiment, one would simply cause the switching unit 1500 to rotate to switch the connections between the ducts running to the high and low vents on the one hand, and the supply and return ducts on the other hand. Each rotation of 90° in the same or opposite direction will switch the ducts from one configuration to the next. Alternatively, the switching unit 1500 could be rotated in forward and reverse directions to accomplish switching.

Although the embodiment illustrated in FIG. 38 is circular, in alternate embodiments, the switching unit 1500 could have alternate shapes, such as square or rectangular. Also, as with the embodiment illustrated in FIG. 37, it would be easy to provide a drive mechanism capable of causing the switching unit 1500 to rotate to switch the duct connections. Any suitable low cost mechanism capable of imparting rotational motion in a single rotational direction, or in alternating rotational directions would suffice.

FIGS. 39-41B illustrate an alternate embodiment of a switching unit 1300. This switching unit 1300 also makes use of a duct system that is arranged in substantially the same way as the duct system illustrated in FIG. 35. However, the switching unit 1300 itself is different.

FIGS. 39-41B illustrate that the top and bottom surfaces of the switching unit 1300 have a substantially trapezoidal shape. The shorter of the two parallel sides 1301 of the switching unit 1300 faces the supply duct 102 and return duct 104. The longer of the two parallel sides 1303 faces the vent ducts 302, 304.

The interior of the switching unit 1300 is divided by a horizontal wall 1302 that extends through the interior of the switching unit 1300 from the short side 1301 to the long side 1303. In addition, both a first shutter 1306 and a second shutter 1308 are rotationally mounted on a vertical center post 1304. The vertical center post 1304 separates both the upper and lower halves of the interior of the switching unit into left and right branches. The first shutter 1306 is mounted above the horizontal wall 1302 and the second shutter is mounted below the horizontal wall 1302.

FIGS. 40A and 40B show the shutters in first positions, while FIGS. 41A and 41B show the shutters in second positions. Specifically, FIGS. 40A and 40B illustrate the first shutter 1306 located in a first position in which it closes off the left branch of the upper half of the switching unit, as seen from FIG. 40A. The second shutter 1308 is in a first position at which it shuts off the right branch of the lower half, as seen from FIG. 40A.

FIGS. 41A and 41B illustrate the first shutter 1306 located in a second position in which it closes off the right branch of the upper half of the switching unit, as seen from FIG. 41A. The second shutter 1308 is in a second position at which it shuts off the right branch of the lower half, as seen from FIG. 41A.

When the first and second shutters 1306, 1308 are in the first positions, as illustrated in FIGS. 40A and 40B, the supply duct 102 is operatively coupled to the vent duct 302 leading to the high vents in a room and the return duct 104 is operatively coupled to the vent duct 304 leading to the lower vents in a room. Thus, the system would be configured for an efficient heating operation.

When the first and second shutters 1306, 1308 are in the second positions, as illustrated in FIGS. 41A and 41B, the supply duct 102 is operatively coupled to the vent duct 304 leading to the low vents in a room and the return duct 104 is operatively coupled to the vent duct 302 leading to the high vents in a room. Thus, the system would be configured for an efficient cooling operation.

A switching unit 1300 as illustrated in FIGS. 39-41B may introduce less flow losses than the switching units illustrated in FIGS. 34-38. In some embodiments, the shutters 1306, 1308 could be manually movable between the first and second positions. In alternate embodiments, one or more power operated drive units could rotate the shutters between the first and second positions to re-configure the system.

FIGS. 42 and 43 illustrate another embodiment of a switching unit 1400 that could used in a duct system as illustrated in FIG. 39. Like the switching unit 1300 discussed above, this embodiment is generally trapezoidal in shape. However, as illustrated in FIGS. 42 and 43, this switching unit 1400 has a distinct left leg 1404 and right leg 1406.

The switching unit 1400 includes a short side 1402 that would be positioned adjacent a supply duct 102 and a return duct 104 that are stacked, as illustrated in FIG. 39. The switching unit includes a horizontal wall 1410 that divides the interior of the switching unit 1400 into an upper and a lower half. The upper half would communicate with the supply duct 102 and the lower half would communicate with the return duct 104.

An upper shutter 1420 is slidably mounted on an upper track 1444. The upper shutter 1420 can slide along the upper track 1444 between a first position in which it blocks the left leg 1404 of the upper portion of the switching unit and a second position in which it blocks the right leg 1406 of the upper portion of the switching unit 1400. In FIG. 42, the first shutter is shown in the first position, in which it blocks the left leg 1404.

A lower shutter 1422 is slidably mounted on a lower track 1446. The lower shutter 1422 can slide along the lower track 1446 between a first position in which it blocks the right leg 1406 of the lower portion of the switching unit and a second position in which it blocks the left leg 1404 of the lower portion of the switching unit 1400. In FIG. 42, the second shutter is shown in the first position, in which it blocks the right leg 1406.

As illustrated in FIG. 43, in some embodiments a motor 1432 for causing the upper and lower shutters 1420, 1422 to move between the first and second positions is located between the left leg 1404 and right leg 1406 of the switching unit 1400. As illustrated in FIGS. 42 and 43, a pinion gear 1430 is mounted on a shaft of the motor 1432. The pinion gear 1430 engages rack gears on the upper shutter 1420 and lower shutter 1422. Rotating the pinion gear in the clockwise direction, as seen in FIG. 42, would cause upper shutter 1420 to move along the upper track 1444 from the first position where it covers the left leg 1404 to the second position at which it covers the right leg 1406. That same clockwise rotation of the pinion gear would also cause the lower shutter 1422 to move along the lower track 1446 from the first position at which it covers the right leg 1406 to the second position at which it covers the left leg 1404. Counterclockwise rotation of the pinion gear 1430 would cause the upper and lower shutters 1420, 1422 to return to the first positions.

When the upper and lower shutters 1420, 1422 are in the first positions, the supply duct 104 would be operatively coupled to the vent duct 302 leading to the high vents and the return duct 104 would be operatively coupled to the vent duct 304 leading to the low vents. Thus, the system would be configured to conduct an efficient heating operation. Causing the upper and lower shutters 1420, 1422 to move to the second positions would reconfigure the system to conduct an efficient cooling operation.

In alternate embodiments, the upper and lower shutters could be manually movable between the first and second positions. Also, alternate power operated drive units could cause movement of the upper and lower shutters between the first and second positions.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A switching unit that couples a supply duct and a return duct leading to a heating and/or cooling system to first and second vent ducts that lead to vents positioned in upper and lower portions of a room of a building, respectively, the switching unit comprising: a main body; a first internal duct that traverses a diagonal path through the main body between a first opening on a first side of the main body and a second opening on a second, opposite side of the main body; and a second internal duct that traverses a diagonal path through the main body between a third opening on the first side of the main body and a fourth opening on the second side of the main body, and wherein the main body is configured to be rotationally mounted.
 2. The switching unit of claim 1, wherein a rotational axis extends from the first side of the main body to the second side of the main body, the rotational axis extending substantially perpendicular to the first and second sides of the main body.
 3. The switching unit of claim 1, wherein the first opening and the third opening are located adjacent diagonally opposite corners of the first side of the main body.
 4. The switching unit of claim 3, wherein the second opening and the fourth opening are located adjacent diagonally opposite corners of the second side of the main body.
 5. A switching unit that couples a supply duct and a return duct leading to a heating and/or cooling system to first and second vent ducts that lead to vents positioned in upper and lower portions of a room of a building, respectively, the switching unit comprising: a substantially rectilinear main body; a first aperture that passes from a first side of the main body to a second opposite side of the main body; and a second aperture that passes from the first side to the second side of the main body, wherein the first and second apertures are located on the first side of the main body diagonally opposite to one another.
 6. The switching unit of claim 5, wherein the first and second sides of the main body are substantially rectangular, and the first and second apertures are located adjacent diagonally opposite corners of the first side.
 7. The switching unit of claim 5, further comprising: a third aperture that passes from the first side of the main body to the second side of the main body; and a fourth aperture that passes from the first side of the main body to the second side of the main body, wherein the third and fourth apertures are located on the first side of the main body diagonally opposite to one another.
 8. The switching unit of claim 7, further comprising: a first shutter that is movably mounted on the main body and that is movable between a first position at which it covers the first aperture and a second position at which it covers the third aperture; and a second shutter that is movably mounted on the main body and that is movable between a first position at which it covers the second aperture and a second position at which it covers the fourth aperture.
 9. The switching unit of claim 8, further comprising at least one drive mechanism for causing the first and second shutters to move back and forth between the first and second positions.
 10. The switching unit of claim 8, further comprising: a first drive unit that causes the first shutter to move back and forth between the first and second positions; and a second drive unit that causes the second shutter to move back and forth between the first and second positions.
 11. The switching unit of claim 8, wherein the first and second shutters are rotationally mounted on the main body.
 12. A switching unit that couples a supply duct and a return duct leading to a heating and/or cooling system to first and second vent ducts that lead to vents positioned in upper and lower portions of a room of a building, respectively, the switching unit comprising: a main body, comprising: upper and lower walls and left and right sidewalls, a horizontally extending interior wall that divides an interior of the main body into an upper section and a lower section, a rear side with upper and lower openings that communicate with the upper and lower sections, respectively, of the interior of the main body, and a front side, opposite the rear side, that is divided into a left leg and a right leg, wherein the front side includes an upper left leg opening and an upper right leg opening that communicate with the upper section of the interior of the main body, and wherein the front side also includes a lower left leg opening and a lower right leg opening that communicate with the lower section of the interior of the main body; an upper shutter than is movably mounted on the upper section of the main body so that the upper shutter can selectively block either the upper left leg opening or the upper right leg opening; and a lower shutter that is movably mounted on the lower section of the main body so that the lower shutter can selectively block either the lower left leg opening or the lower right leg opening.
 13. The switching unit of claim 12, wherein the upper and lower shutters are rotationally mounted on the main body.
 14. The switching unit of claim 13, wherein the main body further includes a center post that extends vertically along the front side of the main body between the left and right legs.
 15. The switching unit of claim 14, wherein side edges of the upper and lower shutters are rotationally mounted on the center post.
 16. The switching unit of claim 12, further comprising at least one drive unit that is configured to move the upper and lower shutters.
 17. The switching unit of claim 12, wherein the upper and lower shutters are slidably mounted on the front side of the main body.
 18. The switching unit of claim 17, further comprising: an upper frame mounted on the front side of the main body, wherein the upper shutter is slidably mounted on the upper frame so that it can move between a first position at which it blocks the upper left leg opening and a second position at which it blocks the upper right leg opening; and a lower frame mounted on the front side of the main body, wherein the lower shutter is slidably mounted on the lower frame so that it can move between a first position at which it blocks the lower right leg opening and a second position at which it blocks the lower left leg opening.
 19. The switching unit of claim 18, wherein a first rack gear is formed on a lower side edge of the upper shutter, wherein a second rack gear is formed on an upper side edge of the lower shutter, and further comprising a pinion gear that is rotationally mounted between the right and left legs of the main body so that it simultaneously engages both the first and second rack gears.
 20. The switching unit of claim 19, wherein rotating the pinion gear in a first rotational direction causes the upper and lower shutters to move from the first positions to the second positions, and wherein rotating the pinion gear in a second opposite rotational direction causes the upper and lower shutters to move from the second positions to the first positions.
 21. The switching unit of claim 20, further comprising a motor that is operationally coupled to the pinion gear.
 22. A switching unit that couples a supply duct and a return duct leading to a heating and/or cooling system to first and second vent ducts that lead to vents positioned in upper and lower portions of a room of a building, respectively, the switching unit comprising: a substantially rectilinear main body having a first side that is configured to be coupled to a supply duct and a return duct that are spaced apart from one another in a first axial direction and a second side that is configured to be coupled to first and second vent ducts that are spaced apart from each other in a second axial direction that is substantially perpendicular to the first axial direction; and a substantially flat switch plate having first and second planer sides that is mountable in the main body, the switch plate including first and second apertures that are positioned diagonally opposite to one another in the switch plate, wherein when the switch plate is located in a first position in the main body, the switch plate operationally couples the supply duct to the first vent duct and the return duct to the second vent duct, and wherein when the switch plate is located in a second position in the main body, the switch plate operationally couples the supply duct to the second vent duct and the return duct to the first vent duct.
 23. The switching unit of claim 22, wherein when the switch plate is located in the first position, the first planer side of the switch plate faces the first and second vent ducts, and wherein when the switch plate is located in the second position, the first planer side of the switch plate faces the supply and return ducts.
 24. The switching unit of claim 22, wherein the switch plate is rotated 90° about a central axis to move the switch plate from the first position to the second position.
 25. The switching unit of claim 22, wherein the switch plate includes a third aperture that is diagonally opposite to the second aperture.
 26. The switching unit of claim 25, wherein when the switch plate is located in the first position in the main body, one of the first and second apertures operationally couples the supply duct to the first vent duct and the other of the first and second apertures operationally couples the return duct to the second vent duct, and wherein when the switch plate is located in the second position in the main body, one of the second and third apertures operationally couples the supply duct to the second vent duct and the other of the second and third apertures operationally couples the return duct to the first vent duct.
 27. The switching unit of claim 26, wherein the switch plate is slidable between the first and second positions. 